ABSTRACT
Chemistry has a history in the emergence debate. Even before the term ‘emergence’ acquired its modern philosophical meaning, John Stuart Mill cited chemical compounds as the bearers of emergent properties that could not be predicted from those of their constituent elements. More specific varieties of emergence result when particular kinds of dependence and novelty are filled in. Many philosophers might reject the idea that there can be strong emergence in chemistry because they think that the reducibility of chemical entities and properties to physical entities and properties, or their identity with physical entities and properties, has been established and expressed in theoretical identities as ‘water is H2O’. Structure is central to chemistry: substances are named and classified by chemists in ways that depend entirely on their structure at the molecular scale, and structure grounds our understanding of their chemical reactivity and spectroscopic behaviour. In an important sense, the identity of a substance depends on its structure at the molecular scale.
